VERRUCAE (WARTS) - pediagenosis
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Monday, March 8, 2021



Verrucae are one of the most frequently encountered viral infections in humans. They are capable of causing disease in any individual, but severe infections seem to be more likely in those who are immunocompromised. Warts can affect any cutaneous surface, and unique wart subtypes are more prone to cause disease in different clinical locations. By far the most important aspect of infection with the human papillomavirus (HPV) is the ability of the virus to cause malignant transformation. This malignant potential is specific to certain subtypes and is especially a concern in women, who are at risk for cervical cancer. Most cases of cervical cancer can be traced to prior infection with certain HPV strains. In June 2006, the U.S. Food and Drug Administration approved the use of a prophylactic HPV vaccine in prepubertal girls. The vaccine is a recombinant quad-rivalent vaccine against HPV types 6, 11, 16, and 18. Types 16 and 18 are believed to have been responsible for up to 70% of cervical cancers.

Clinical Findings: Verruca vulgaris, also called the common wart, is the most prevalent wart that infects the human. It can be located on any cutaneous surface. These warts often appear as small papules with a rough surface studded with pinpoint, dark purple to black dots. These dots represent the thromboses of the tiny capillaries within the wart. Most warts are between 5 mm and 1 cm in diameter, but some can become quite large and encompass much larger areas of the skin. The coalescence of multiple warts into one larger wart is called mosaic warts. These are most commonly seen on the plantar aspect of the foot. Verruca vulgaris can come in many sizes and shapes. Most lesions spontaneously resolve within a few years. A good rule of thumb is that 50% of verrucae will disappear spontaneously in 2 years. Many distinctive clinical forms of warts exist.


The filiform wart is represented by a small verrucal papule with finger-like projections extruding from the base of the papule. The projections are typically 1 to 2 mm thick and 4 to 7 mm long. They are commonly found on the face. The flat wart is frequently encountered and manifests as a 3- to 5-mm, flat papule with a slight pink to red to purple coloration. Flat warts are frequently seen on the legs of women and in the beard region of men, and they can be arranged in a linear pattern if the warts are spread during the act of shaving. Flat warts have been found to be highly associated with HPV types 3 and 10.

Plantar warts (myrmecia) are seen on the plantar aspect of the foot and are caused for the most part by HPV types 1, 2, and 4. They are deep-seated papules and plaques that may coalesce into large mosaic warts.

The warts are well defined and characteristically interrupt the skin lines. This is in contrast to a callus, in which the skin lines are retained, and this sign can be used to differentiate the two conditions. Plantar warts can cause pain and discomfort if they are located in areas of pressure such as the heels or across the skin underlying the metatarsal heads. Palmar warts are very similar to plantar warts and have the same clinical appearance.

Subungual and periungual warts, a subclassification of palmar/plantar warts, are found around and under the nail apparatus. These warts can cause nail dystrophy and pain on grasping of objects. They tend to affect more than one finger and can be more difficult to treat than the common wart. Long-standing periungual or subungual warts that have a changing morphology should be biopsied to rule out malignant transformation into a squamous cell carcinoma. This is not infrequently encountered, and a high clinical suspicion should be used when investigating these types of warts. Ring warts are seen after various treatments of common warts, most frequently after liquid nitrogen therapy. The central portion of the wart resolves, leaving a ring-shaped or donut-shaped wart with central clearing. These warts can become larger than the wart originally treated.

Condylomata acuminata (genital warts) are often considered to be the most common form of sexually transmitted disease in the United States. These warts typically begin as small, flesh-colored to slightly hyper-pigmented macules and papules. As they grow, they take on an exophytic growth pattern and have often been compared with the appearance of cauliflower. The warts may stay small and localized, or they may grow to enormous size, leading to difficulty with urination and sexual intercourse. Females with cervical genital warts are asymptomatic and may not realize they are infected. Routine gynecological examinations and Papanicolaou smears are the only reliable way to diagnosis cervical warts. Diagnosis is extremely important, because cervical warts are the number one cause of cervical cancer.

Histology: Skin biopsies of wart tissue show the pathognomonic cell called the koilocyte. This cell, when present, is highly specific and sensitive for HPV infection. It is a keratinocyte with a basophilic small nucleus and a surrounding clear halo. There are few to no keratohyalin granules in the koilocyte. Other findings include varying amounts of hyperkeratosis, acanthosis, and striking papillomatosis.


Pathogenesis: Warts are caused by infection with HPV, of which more than 150 subtypes are known to cause human disease. They are small viruses with no lipid envelope, and they can stay viable for long periods. HPV has a double-stranded, circular DNA. A variety of subtypes are able to affect different regions of the body. HPV is capable of infecting human epithelium, including the keratinized skin and the mucous membranes. It gains entry through slightly abraded skin or mucous membranes. The virus does not actively infect the outer stratum corneum but rather the stratum basalis cells. Like most viruses, HPV can produce early and late gene products. The early genes encode various proteins necessary for replication. These early gene products also play a role in malignant transformation of the infected cell. The exact mechanism is not completely understood. The late genes produce capsid proteins. At least eight early genes are present, and two late genes are included in the viral DNA.

Treatment: Common warts can be treated in a number of ways. Approximately 50% of the lesions spontaneously resolve. The others may or may not respond to therapy. This lack of universal treatment response is frustrating to patient and physician alike. Many destructive therapies are available, including liquid nitrogen cryotherapy, salicylic acid, trichloracetic acid, cantharidin, podophyllin, and bleomycin. Immunotherapy can be used to induce an immunological response; these options include imiquimod, interferon, squaric acid, and Candida skin test antigen. No single therapy appears to work better than any other, and patients often need to undergo a variety of treatments until they find one that works.

Genital warts should be treated with imiquimod or one of the destructive methods to decrease the risk of transmission. Women who are sexually active should undergo routine gynecological screening. The advent of the HPV vaccine may lead to a d creased incidence of genital warts and cervical cancer.

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